Zebrafish has emerged as a premiere organism to study vertebrate development and genetics. Powerful techniques allow efficient generation and recovery of zebrafish mutations affecting genes that regulate developmental patterning, organogenesis, physiology, and behavior. Recent advances make it easy to study gene function in transgenic zebrafish and with antisense oligonucleotides. The functions of many of these genes are conserved among vertebrate groups. Thus, analysis of zebrafish mutations provides insights into gene function in other vertebrates, including humans. The Zebrafish Iinternational Resource Center has been established as a repository that provides animals, materials, and services to the research community. This proposal seeks continued funding to: 1) provide a centralized repository for zebrafish genetic stocks and research materials; 2) provide consultation and pathology services; and 3) develop improved zebrafish husbandry methods. These materials, services, and information will be made widely available to the research community.